Intracellular Released Payload Influences Potency and Bystander-Killing Effects of Antibody-Drug Conjugates in Preclinical Models

Abstract

Antibody-drug conjugates (ADC) comprise targeting antibodies armed with potent small-molecule payloads. ADCs demonstrate specific cell killing in clinic, but the basis of their antitumor activity is not fully understood. In this study, we investigated the degree to which payload release predicts ADC activity in vitro and in vivo. ADCs were generated to target different receptors on the anaplastic large cell lymphoma line L-82, but delivered the same cytotoxic payload (monomethyl auristatin E, MMAE), and we found that the intracellular concentration of released MMAE correlated with in vitro ADC-mediated cytotoxicity independent of target expression or drug:antibody ratios. Intratumoral MMAE concentrations consistently correlated with the extent of tumor growth inhibition in tumor xenograft models.

Orthogonal Cysteine Protection Enables Homogeneous Multi‐Drug Antibody–Drug Conjugates

“…However, MMAE is also a substrate for MDR exporters and has diminished activity on cells with high pump expression 8. Conversely, MMAF and cys‐mcMMAF, released from mc‐vc‐MMAF and mc‐MMAF ADCs, respectively, are not susceptible to drug export and retain activity on MDR(+) cells but are minimally cell permeable 7b, 9. Thus, they do not exhibit bystander activity and have little activity on antigen‐negative tumor cells.…”

“…Encouraged with these in vitro results, we tested the same conjugates in an in vivo model that has heterogeneous CD30 expression. The xenograft model consists of an admixed population of CD30(+) and CD30(−) Karpas 299 cells 7b. In this model, cAC10‐ 1 showed only a modest tumor growth delay when dosed at 3 mg kg −1 .…”

Therapeutic potential of SGN-CD19B, a PBD-based anti-CD19 drug conjugate, for treatment of B-cell malignancies

“…cys-mcMMAF, the drug released by SGN-CD19A, 43 has a low octanol-water partition coefficient (Jocelyn Setter, unpublished observations), rendering it far less permeable to the plasma membrane and thereby unable to attain the bystander activity ascribed to MMAE and PBD ADCs. 44 Bystander activity can be advantageous when tumor antigen expression is heterogeneous. 44 However, the reduced uptake of cys-mcMMAF into nontargeted cells may mitigate toxicity, which could explain why SGN-CD19A shows reduced myelosuppression, minimal neuropathy, and improved overall tolerability when compared with other ADCs.…”

“…44 Bystander activity can be advantageous when tumor antigen expression is heterogeneous. 44 However, the reduced uptake of cys-mcMMAF into nontargeted cells may mitigate toxicity, which could explain why SGN-CD19A shows reduced myelosuppression, minimal neuropathy, and improved overall tolerability when compared with other ADCs. 12,45 SGN-CD19B, on the other hand, offers the potential for robust activity against refractory B-cell malignancies but may induce more myelosuppression than SGN-CD19A.…”

Entwicklung Pyrrolobenzodiazepin(PBD)‐haltiger Antikörper‐Wirkstoff‐Konjugate (ADCs) ausgehend von Anthramycin

“…Seattle Genetics hat auch Studien über den Zuschauereffekt verçffentlicht, der mit PBD-haltigen ADCs assoziiert wird. [106] Es wurde gezeigt, dass ein ADC mit einem auf CD30 + abzielenden Antikçrper, der an ein MC-Val-Ala-PBD-Dimer-Konstrukt konjugiert ist (identisch zu dem, das bei CD33A, SGN-CD70A und SGN-CD123A verwendet wurde), im Unterschied zu einem weniger gut membrangängigen CD30…”